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    <title>Document</title>
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    <script>
       /*  var a=80
        switch(true){
            case a<60:
                console.log('不及格')
                break
            case a>=60&&a<70:
                console.log('及格')
                break
            case a>=70&&a<80:
                console.log('良好')
                break
            case a>=80&&a<90:
                console.log('优秀')
                break
            case a>=90&&a<=100:
                console.log('xb')
                break        
        } */

        var a=prompt()
        if(a<60){
            console.log('不及格')
        }else if(a>=60&&a<70){
            console.log('及格')
        }else if(a>=70&&a<80){
            console.log('良好')
        }else if(a>=80&&a<90){
            console.log('优秀')
        }else if(a>=90&&a<=100){
            console.log('xb')
        }
    </script>
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